SAT Math Multiple Choice Question 631: Answer and Explanation

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Question: 631

1. If 2b - 1 = 5, what is the value of 2b2 - 1?

  • A. 15
  • B. 17
  • C. 24
  • D. 25

Correct Answer: B

Explanation:

B

Algebra (solving equations) EASY

Original equation:

2b - 1 = 5

Add 1:

2b = 6

Divide by 2:

b = 3

Substitute b = 3 into 2b2 - 1:

2b2 - 1 = 2(3)2 - 1 = 18 - 1 = 17

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